Media storage systems are commonly used to store data cartridges and to retrieve desired data cartridges so that computer readable data may be written to or read from the data cartridges. As such, large volumes of computer readable data can be stored on numerous data cartridges and accessed by a single computer or by multiple computers connected to the media storage over a network. Such media storage systems are often referred to as “juke box” storage systems, and may include a cartridge storage rack or “magazine” and a cartridge read/write device. The cartridge storage rack serves as a storage location for the data cartridges. Multiple storage racks are commonly arranged so that they form one or more adjacent vertical stacks which define a single cartridge access plane. In multi-plane media storage systems, storage racks and read/write device(s) may be positioned across from one another, or arranged in a U-shaped configuration. The media storage system also includes a cartridge access device for moving among and accessing the data cartridges stored therein. In multi-plane media storage systems where storage racks are positioned across from one another, the cartridge access device may be positioned between the storage rack planes.
When a computer connected to the media storage system issues a request to access a data cartridge to read and/or write data thereto, a control system moves the cartridge access device among the storage racks until the cartridge access device is positioned adjacent the requested data cartridge. The cartridge access device then removes the data cartridge from the storage rack and delivers it to the read/write device for the computer to access the computer readable data stored thereon.
Once a request to access a data cartridge is received, the control system must be able to locate or otherwise recognize the requested data cartridge in the storage rack. One solution is to maintain a “map” indicating the identity and position of each data cartridge in the storage rack. However, the map must be periodically updated to ensure that the map contains accurate data. Events that will usually indicate a need to update the map include, but are not limited to, adding or removing a data cartridge from the system, operating a cartridge “mail slot”, or a system power cycle (i.e., if the data storage system is turned off). Likewise, when the computer readable data contained on an existing data cartridge in the storage rack is changed, the map must be updated to reflect the changed content of the data cartridge at that position. Other examples where the map must be updated include, moving a data cartridge to another position in the storage rack, adding another storage rack to the media storage system, or otherwise changing the configuration of the system.
One solution to maintaining the map is to manually inventory the media storage system each time a change occurs. However, this is time consuming and prone to human error. Another solution for maintaining the map is to label each data cartridge stored in the media storage system with a machine-readable code, such as a bar code label and to read the bar code label with a scanner attached to the cartridge access device. However, the data cartridges may be positioned in the storage rack in close proximity to one another. Therefore, the cartridge access device and the data cartridge must be carefully aligned to correctly scan the bar code. Furthermore, the bar code only contains limited information (e.g., an identification number), and cannot be rewritten. Any further information must be stored separately (e.g., in a “look-up” table or other suitable database). For example, a “lookup” table may associate the identification number contained on the bar code with a date, data format, data type, etc.
Therefore, a need exists for a system to read and store the cartridge identification and other data related to the data cartridge. Ideally, such a system can store the cartridge identification and other data without the need for separate “look-up” tables. In multi-plane systems, it would be most desirable to provide such a system which can quickly and efficiently read and store data from cartridges located in multiple cartridge access planes.